Evaporator for absorption type refrigerating systems



Oct. 18, 1955 Q DOEBELI 2,720,763

EVAPORATOR FOR ABSORPTION TYPE REFRIGERATING SYSTEMS Filed May 16, 1952 HIIIWIUIII United States Patent EVAPORATOR FOR ABSORPTIGN TYPE REFRIGERATING SYSTEMS Oscar Doebeli, Zurich, Switzerland Application May 16, 1952, Serial No. 288,142

Claims priority, application Switzerland May 16, 1951 3 Claims. (Cl. 62126) The present invention relates to an evaporator for absorption type refrigerating systems, particularly to a flat evaporator of the kind used for instance in horizontally extending cooling compartments.

In order to enable the evaporating refrigerating medium to wet a free surface which is as big as possible, it has been proposed to slope the evaporator so that the refrigerating medium will flow through the evaporator. However, this slope easily is illusive, if the casing in which the evaporator is mounted is tilted in the direction opposite to said slight slope. This often occurs with refrigerators standing on an uneven floor.

Attempts have been made to enlarge the surface of the evaporating medium by filling the evaporator with rings, granules, porous substances etc., through which the evaporating medium flows. It has been found that such fillings are not as eflicient as expected, because the disposable amount of the medium is too small and cannot be distributed so widely.

These drawbacks are removed by the evaporator according to the invention, which includes a tube having at least one woven layer of a material which is absorbent and inert with respect to the refrigerating medium and is in contact with the internal surface of the tube only along the bottom portion of the latter.

The accompanying drawings show some examples of evaporators according to the invention.

Fig. l is a front view of an evaporator made of circular tubes.

Fig. 2 is a plan view of Fig. 1,

Fig. 3 shows a cross-section along the line IIIHI in Fig. 2 in a larger scale,

Fig. 4 is a front view of an evaporator made of squared tubes,

Fig. 5 is a plan view of Fig. 4,

Fig. 6 is a side view of an evaporator comprising two concentric tubes arranged one within the other, partially in section,

Fig. 7 shows a cross-section of the evaporator of Fig. 6,

Fig. 8 shows a vertical section of a further example of an evaporator, and

Fig. 9 is a plan view of one end portion of the evaporator of Fig. 8.

The evaporator shown in Figs. 1 to 3 is made of a bent tube 1 of circular cross-section and contains along the bottom of the horizontally disposed windings a woven layer 2 formed of a material which is absorbent and inert with respect to the evaporating medium, preferably a fabn'c of glass threads. This layer may be just laid in, or may be fixed in any suitable manner.

The only difference between the evaporator according to Figs. 1 to 3 and that according to Figs. 4 and 5 is seen in the use of squared tubes 3 in the latter example instead of the tubes 1 having a circular cross-section.

If the evaporator consists of two concentric tubes 4 and 5 (Figs. 6 and 7), preferably a woven layer 6 in the form of a hose pipe is used, which is drawn over the inner tube 5 and hangs on that tube, so that only the lower portion of the hosepipe bears against the bottom of the inside surface of the outer tube 4.

In the evaporator according to Figs. 8 and 9, having a U-shaped cross-section, a piece of woven layer 7 is hung on supports 8 in such a way that the bottom of the evaporator is covered for the major portion by the layer 7.

In all of the evaporators, which could also have a usual form not shown in the drawing, the woven layer serves to distribute the evaporating refrigerating medium over the bottom of the evaporator throughout the length of the latter, by capillary action, and under certain circumstances also enables an accumulation of the refrigerating medium, which may be present in the cycle in a somewhat greater amount as usual. This results in a uniform operation of the refrigerating system when the required amount of cold fluctuates, i. e. when the cooling space and outside temperatures changes.

The absorbent effect of the woven layer makes it unnecessary to slope the evaporator or the evaporator wind ings from the inlet opening, and despite this the proper distribution of the refrigerating medium is achieved, since the capillary action of the fabric automatically gives such a distribution.

A further advantage of the described evaporator not having a slope is the possibility to use its top surface as a support since it may be arranged exactly horizontally.

What I claim is:

1. An evaporator for absorption type refrigerating systerns; said evaporator comprising an elongated tube for receiving a liquid refrigerant at one end, and at least one layer of a glass fiber fabric disposed in said tube and in contact with the internal surface of said tube along the bottom of the latter, the remainder of said internal surface of the tube being bare so that said last fibre fabric conducts the liquid refrigerant along said tube by capillary action from said one end to the other end of said tube and serves to laterally constrain the liquid refrigerant to the bottom of the tube.

2. An evaporator according to claim 1; wherein said layer is relatively narrow and in contact with said internal surface of the tube across the entire width of said layer.

3. An evaporator according to claim 1; wherein a support tube of smaller diameter extends axially through the first mentioned tube, and said layer is of tubular configuration and has a circumference larger than that of said support tube to hang from said support tube with only a portion of said tubular layer being in contact with said internal surface of the first mentioned tube at the bottom of the latter.

References Cited in the file of this patent UNITED STATES PATENTS 2,307,947 Payne Ian. 12, 1943 2,565,221 Gaugler Aug. 21, 1951 FOREIGN PATENTS 214,001 Switzerland June 16, 1941 661,541 Great Britain Nov. 21, 1951 988,953 France Sept. 3, 1951 

